import sys
input = sys.stdin.readline


N, K = map(int, input().split())
st = set([input().rstrip() for _ in [0] * N])

visited = set([])
for sv in st:
	if(sv in visited):
		continue
	stk = [sv]
	while(stk):
		v = stk.pop()
		for i in range(K):
			if(v[i] == 'D'):
				continue
			nv = ''.join([v[:i],chr(ord(v[i])+1),v[i+1:]])
			if(nv in visited):
				continue
			visited.add(nv)
			stk.append(nv)

ans = len(visited & st)
print(ans)